I have some idea to prevent spam:
Implement SMAS to all campaign managers and must be managed by the moderators if an user listed to SMAS moderators can disable the signature of that user preventing the user from joining signature campaigns only problem is can moderators disable signature remotely? I think this more humane than giving negative feedback

Although giving users a negative feedback helps a lot against spamming and shitposting, the problem is, the feedback is harsh and also, the user given a negative trust by the DT user posts in reputation section pleading to remove their negative feedback or attacking the DT who gave him/her a negative feedback making more spam in reputation and Meta sections...